Which aluminum alloy did Dan Shechtman study when he discovered quasicrystals?

In 1982, while conducting research at the National Bureau of Standards, Dan Shechtman investigated the metallurgical properties of aluminum–iron and aluminum–manganese alloys.1

He discovered quasicrystals specifically while studying the aluminum–manganese alloy, which he and his colleagues created by mixing the two elements in a roughly six-to-one proportion, melting them, and then rapidly cooling the mixture. Upon examining the solidified alloy with an electron microscope, he observed an unexpected fivefold symmetry, which challenged the long-held scientific belief that such structures were impossible in crystals.1